Magnetic Resonance Imaging (MRI) has emerged in the past decade as an important tool for the detection, diagnosis and management of breast cancer. However, the availability and reliability of MRI guided interventional procedures have lagged behind. Currently, ultrasound (US) image-guided breast biopsy is favored by many clinicians for MRI-detected lesions, as it provides real-time imaging of the biopsy process and it is relatively easy and low cost to use. With US the ability to control and monitor the biopsy in real-time provides a high level of confidence regarding the success of lesion sampling. However, US does not provide the detection sensitivity offered by MRI and this approach requires shuffling patients between MRI and US suites, disrupting workflow and causing costly delays and increasing patient anxiety. More importantly, many breast lesions can only be detected with MRI and the malignancy rate is too high (22%) to not biopsy these lesions. Where appropriate, MRI could also be used more effectively to guide and monitor minimally invasive thermal ablation treatment of tumors. Hypothesis: We hypothesize that a new interventional robotic platform for guiding breast biopsy procedures inside the bore of the MRI scanner, using real-time MRI for interactive control and monitoring of the procedure, will allow interventionists to perform MRI guided breast biopsies much more quickly and more precisely than with current MRI-assisted biopsy methods. Preliminary Data: We have developed a robotic interactive MR Imaging Guided Biopsy (iMR-IGB) proof-of-concept prototype system and demonstrated that it can work by remote control inside the bore of an MRI scanner during real-time imaging. This prototype system has been assessed for potential adverse impacts on imaging quality with typical MRI sequences used for breast cancer diagnosis and biopsy, and was determined by expert breast MRI radiologists to be very likely suitable for interactively guiding breast biopsies These imaging quality assessments were performed with both tissue mimicking phantoms and with human subject volunteers, and imaging quality was found to be acceptable in both scenarios. Specific Aims: Our first aim is to advance the development of the iMR-IGB robotic system hardware and control software from proof-of-concept prototype to a level of functionality, safety and operational integrity suitable for performing initial human clinical evaluations. We wil demonstrate functional performance in-bore in simulated biopsy procedures with ex-vivo tissue by systematically and consecutively targeting an array of typical lesion locations within ?1 mm targeting accuracy using the robotics control subsystem. Our second aim is to fully integrate the control subsystems: Robotics Power and Control; Scanner Interface; and Clinical Workstation/User Interface, with the iMR-IGB hardware developed in Aim 1. We will then use the fully integrated system to repeat the demonstration of functional performance from aim 1, and to successfully complete an ex-vivo biopsy simulation by a radiologist. The final aim is to acquire FDA IDE approval, then achieve IRB approval of a new protocol for clinical evaluations.